duramax 6.6 lml

I just bought a 13 lml. 155,000 miles. Test drove it all sounded great. After about 300 miles I started hearing a knock, hooked computer up and cylinder 6 balance rate was at -4.2. Changed injector same problem. The noise only comes when the truck it warm or up to temp. I can unplug injector...

I am new to the diesel world so I figured Id ask anyone here with knowledge. I have a 2016 LML 6.6 Duramax 75,800 miles, the only modifications on the truck is a S&B cold air intake. I'm wanting to know if I need to delete the DPF, EGR, and the DEF in order to tune the truck. I know i can throw...